Due to the low conductivity of composites, and particularly carbon fiber, the need to protect them against electrical discharges when they are used in aircraft structures is well known.
A lightning protection is needed in the joint areas of aircrafts components made of composite material, especially CFRP (Carbon Fibre Reinforced Plastic), with another components by means of metallic fasteners and specially needed when the inner component is made of a metallic material as happens in the case of the joint areas of a wing skin with a fuel tank.
Patents or patent applications EP 0976 652, EP 0976 653, EP 1 484 245 and WO 2006/069996 in the name of the applicant disclose lightning protection arrangements in said joint areas.
The current trend in the aeronautic industry to use composite materials instead of metallic materials for aircraft structures with an aerodynamic contour such as lifting surfaces and fuselages has opened new needs of lightning protection arrangements in large aircrafts components made of composite material as happens when a metallic part is joined to an aircraft component by its outer surface. One example of these new needs is the joint area between a metallic drip fence and a CFRP wing skin where phenomena like hot spots or electric arcs generated in lightning events may cause severe damages in the wing skin. In addition in a metallic to CFRP joint is necessary a corrosion protection between the parts.